Difference between revisions of "Straight line control points"
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The panorama tools optimiser understands various different schemes for | The panorama tools optimiser understands various different schemes for | ||
aligning photos using [[control points]]: | aligning photos using [[control points]]: |
Revision as of 21:34, 18 November 2007
The panorama tools optimiser understands various different schemes for
aligning photos using control points:
Normal points are t0 points, horizontal control points are t1 points and
vertical control points are t2 points.
Straight line control points were added later and have a similar effect to horizontal and vertical points, except that the straight line can be at any angle. They have two main uses: Lining up linear features that don't have identifiable detail, such as the edges of a room or overhead cables; and calibrating lens distortion using a single rectilinear photograph of a grid or building.
Although two points are sufficient to define a horizontal or vertical line, more are required for these lines at arbitrary angles. Since the script file format only supports 'pairs' of points, a straight line is generally defined with four, six or eight etc... control points.
Some of the GUI front-ends support placing these straight line control points, see this tutorial on correcting lens distortion with ptgui.
Otherwise if you edit a PTOptimizer script and make more than one pair of existing points t3, then the optimiser will try to line them up as a straight line in the output image. You can keep going, with t4, t5 etc... for each group of points that you want in different 'straight lines'.